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831.
832.
We have used perturbation theory for a many-particle system to analyze intersubband emission in quantum wells, taking into
account Coulomb interaction of electrons. We obtained approximate analytical expressions for the shape factor for homogeneous
broadening for intersubband transitions. We analyzed the effect of the excitation level and the temperature on the spectral
lineshapes.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 642–647, September–October, 2007. 相似文献
833.
I.S. Burns J. Hult G. Hartung C.F. Kaminski 《Proceedings of the Combustion Institute》2007,31(1):775-782
We report on the development of a novel diode laser thermometry technique permitting temperature measurements in flames based on the fluorescence lineshapes of an atomic tracer species. The technique, which we term OLAF (one-line atomic fluorescence) requires only a single diode laser source for excitation, is simple to implement, and has excellent spatial resolution. Temperatures are deduced from the 52P1/2 → 62S1/2 transition of atomic indium, the lineshape of which is highly sensitive to temperature changes at typical flame conditions. A rigorous validation is performed in a reference flame with comparisons to measurements by CARS and by Na-line reversal, and to numerical simulations. 相似文献
834.
Single detector and coincidence Doppler broadening (CDB) spectroscopy measurements using slow positron beam were carried out to study as-deposited and annealed Ti/Al multilayer films. The changes of the film structure and defects in each layer by heat treatment have been investigated through the analysis of Doppler broadening lineshape variation. The coincidence Doppler broadening measurements revealed that Ti is the dominant diffusion species during the alloying process of Ti/Al by high temperature annealing. These results highlight the potential of slow positron beam in characterizing the vacancy-type defects evolution and mechanism of interlayer diffusion in Ti/Al multilayer film. 相似文献
835.
光强调谐曲线是激光陀螺工作模式选取和稳频的依据,而陀螺的增损比将直接决定光强调谐曲线的形式.为了提高陀螺准确度,本文对双同位素综合展宽情况下二频激光陀螺出光带宽与增损比之间的关系进行了分析计算,结果表明,激光陀螺的出光带宽与增损比之间存在单调递增的变化关系.数值仿真了不同增损比情况下陀螺的光强调谐曲线,结果表明,根据激光陀螺出光带宽与相邻纵横间隔相对大小的不同,其光强调谐曲线的形状可分三种,仿真与试验结果非常吻合.分析并试验验证了增损比选取不当对激光陀螺工程化应用可能产生的影响,给出了不同腔长情况下激光陀螺增损比合理选取的参考值,即应保证陀螺的出光带宽约等于其相邻纵横间隔. 相似文献
837.
Nicola Tasinato Arianna Turchetto Cristina Puzzarini Paolo Stoppa Andrea Pietropolli Charmet Santi Giorgianni 《Molecular physics》2014,112(18):2384-2396
Hydrofluorocarbons have been used as replacement gases of chlorofluorocarbons, since the latter have been phased out by the Montreal Protocol due to their environmental hazardous ozone-depleting effects. This is also the case of difluoromethane (CH2F2, HFC-32), which nowadays is widely used in refrigerant mixtures together with CF3CH3, CF3CH2F, and CF3CHF2. Due to its commercial use, in the last years, the atmospheric concentration of HFC-32 has increased significantly. However, this molecule presents strong absorptions within the 8–12 μm atmospheric window, and hence it is a greenhouse gas which contributes to global warming. Although over the years several experimental and theoretical investigations dealt with the spectroscopic properties of CH2F2, up to now pressure broadening coefficients have never been determined. In the present work, the line-by-line parameters of CH2F2 are retrieved for either ground state or ν7 band transitions by means of microwave (MW) and infrared (IR) absorption spectroscopy, respectively. In particular, laboratory experiments are carried out on 9 pure rotational transitions of the ground state and 26 ro-vibrational transitions belonging to the ν7 band lying around 8.2 μm within the atmospheric region. Measurements are carried out at room temperature on self-perturbed CH2F2 as well as on CH2F2 perturbed by N2 and O2. The line shape analysis leads to the first determination of self-, N2-, O2-, and air-broadening coefficients, and also of line intensities (IR). Upon comparison, broadening coefficients of ground state transitions are larger than those of the ν7 band, and no clear dependence on the rotational quantum numbers can be reported. The obtained results represent basic information for the atmospheric modelling of this compound as well as for remote sensing applications. 相似文献
838.
Pingping Sun Dean Liu Yanli Zhang Yan Zhang Fang Liu Xuejie Zhang Jianqiang Zhu 《Optik》2011,122(24):2230-2233
By means of Collins diffraction integral, the propagation expression of an ultrashort laser pulse passing through a spatial filter is derived. The effects of the magnification of spatial filter on pulse broadening and distortion of pulse-front for the ultrashort optical pulse are analytically deduced and numerically simulated. It is found that pulse broadening and propagation time difference of a laser pulse getting through spatial filter is proportional to the magnification. As a conclusion, in an ultrashort pulse laser system with a large aperture, the effect of pulse broadening and distortion of pulse-front should be considered. 相似文献
839.
Shun Miyano 《Journal of Molecular Spectroscopy》2011,265(1):47-51
Mid-infrared absorption spectroscopy was applied to the detection of the hydroperoxyl radical (HO2) in pulsed laser photolysis combined with a laser absorption kinetics reactor. The transition of the ν3 vibrational band assigned to the O-O stretch mode around 1065 cm−1 was probed with a thermoelectrically cooled, continuous wave, mid-infrared, distributed feedback quantum cascade laser (QCL). The HO2 was generated through 355 nm photolysis of Cl2/1,4-c-C6H8/O2 mixtures. The mid-infrared absorption spectrum of the HO2 radical was recorded between 1064 and 1065.5 cm−1. The absorption line shapes were well represented by the Voigt profile. The nitrogen-broadening coefficients of the HO2 radical at 295 K were determined for four absorption lines around 1065 cm−1. Mid-infrared absorption detection using a QCL as a spectroscopic light source is a powerful method in spectroscopic and kinetics studies of the HO2 radical. 相似文献
840.
C.P. McRaven M.J. Cich Trevor J. Sears Daniel Hurtmans 《Journal of Molecular Spectroscopy》2011,266(1):43-51
We report measurements of self- and nitrogen-pressure broadening of the P(11) line in the ν1 + ν3 combination band of acetylene at 195 739.649 5135(80) GHz by absorption of radiation emitted by an extended cavity diode laser referenced to a femtosecond frequency comb. Broadening, shift and narrowing parameters were determined at 296 K. For the most appropriate, hard collision, model in units of cm−1/atm, we find 0.146317(27), 0.047271(104) and −0.0070819(22) for the acetylene self-broadening, narrowing and shift, and 0.081129(35), 0.022940(74) and −0.0088913(25) respectively, for the nitrogen-broadening parameters. The uncertainties are expressed as one standard deviation (in parenthesis) in units of the last digit reported. These parameters are 2-3 orders of magnitude more precise than those reported in previous measurements. Similar analyses of the experimental data using soft collision and simple Voigt lineshape models were made for comparison. 相似文献